1. Field of Invention
This invention pertains generally to machines such as engines, pumps, and the like and, more particularly, to a positive displacement internal combustion engine and method.
2. Related Art
For more than a century, internal combustion engines have been relied upon a principal source of power in a variety of applications. Of those engines, the most widely used are the reciprocating piston engines which are found in automobiles and other forms of transportation, as well as in a variety of industrial and consumer applications. Such engines can be built in a variety of sizes, depending upon the power requirements of a particular application, ranging from a single cylinder up to 32 cylinders or more. Other types of internal combustion engines such as rotary engines and internally combusted turbines are also used in a number of applications, but not as widely as the reciprocating piston engines.
Smaller internal combustion engines, including the ones used in most automobiles, are powered by gasoline. However, diesel engines are also used in some automobiles, although they are more commonly found in larger applications such as locomotives and ships.
All of these engines have certain limitations and disadvantages. In reciprocating piston engines, the pistons must stop and reverse direction four times per revolution of the output shaft in a 4-stroke engine and two times per output shaft revolution in a 2-stroke engine. Those engines also require rather complex valve systems in order to get the fuel mixture and the exhaust gases into and out of the combustion chambers at the proper times.
Rotary engines such as the Wankel engine (U.S. Pat. No. 2,988,065) avoid the problem of piston stoppage and reversal, and in addition can provide one power stroke for each revolution of the rotor and shaft, whereas a 4-stroke reciprocating piston engine which has only one power stroke for every two revolutions of the shaft. Notwithstanding those advantages, however, rotary engines have found only limited use due to poor fuel economy, short operating life, and dirty exhaust.
It is in general an object of the invention to provide a new and improved internal combustion engine and method.
Another object of the invention is to provide an internal combustion engine and method of the above character which overcome the limitations and disadvantages of the prior art.
Another object of the invention is to provide an internal combustion engine and method of the above character which provide significantly more power strokes per shaft rotation than reciprocating piston engines and rotary engines heretofore provided.
Another object of the invention is to provide an internal combustion engine and method of the above character which provide a large displacement in a small space.
These and other objects are achieved in accordance with the invention by providing an internal combustion engine and method in which pistons on different rotors move relative to each other to form chambers of variable volume in a toroidal cylinder. The pistons move in stepwise fashion, with the pistons on one rotor travelling a predetermined distance while the pistons on the other rotor remain substantially stationary. Fuel is drawn into a chamber as one of the pistons defining the chamber moves away from the other, and then compressed as the second piston moves toward the first. Combustion of the fuel drives the first piston away from the second, and the spent gases are then expelled from the chamber by the second piston moving again toward the first.
The rotors are connected to an output shaft in such manner that the shaft rotates continuously as the pistons and rotors turn in their stepwise fashion to provide smooth, continuous power. In the embodiments disclosed, a pair of crankshafts are mounted on a carrier affixed to the shaft, and rotated continuously about their axes by connecting rods connected to cranks which turn with the rotors. Gears on the crankshafts transfer this continuous rotation to carrier and shaft as they travel about a sun gear disposed coaxially of the shaft.
With four pistons on each rotor and a 4:1 ratio between the sun and crankshaft gears, eight chambers are formed between the pistons, and there are two power strokes in each of those chambers for each revolution of the output shaft. In two shaft revolutions, there are 32 power strokes, which is equivalent to having 32 cylinders in a conventional 4-stroke engine.